netdev - Re: [PATCH bpf-next v3 1/4] bpf: crypto: Use the correct destructor kfunc type

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Message-ID: <66f4a64c-a6fa-478b-bc79-495a9def10c8@linux.dev>
Date: Mon, 28 Jul 2025 16:07:49 -0700
From: Yonghong Song <yonghong.song@...ux.dev>
To: Sami Tolvanen <samitolvanen@...gle.com>, bpf@...r.kernel.org
Cc: Vadim Fedorenko <vadim.fedorenko@...ux.dev>,
 Alexei Starovoitov <ast@...nel.org>, Daniel Borkmann <daniel@...earbox.net>,
 Andrii Nakryiko <andrii@...nel.org>, Martin KaFai Lau
 <martin.lau@...ux.dev>, Eduard Zingerman <eddyz87@...il.com>,
 Song Liu <song@...nel.org>, John Fastabend <john.fastabend@...il.com>,
 KP Singh <kpsingh@...nel.org>, Stanislav Fomichev <sdf@...ichev.me>,
 Hao Luo <haoluo@...gle.com>, Jiri Olsa <jolsa@...nel.org>,
 Jamal Hadi Salim <jhs@...atatu.com>, Cong Wang <xiyou.wangcong@...il.com>,
 Jiri Pirko <jiri@...nulli.us>, netdev@...r.kernel.org,
 linux-kernel@...r.kernel.org
Subject: Re: [PATCH bpf-next v3 1/4] bpf: crypto: Use the correct destructor
 kfunc type



On 7/28/25 1:26 PM, Sami Tolvanen wrote:
> With CONFIG_CFI_CLANG enabled, the kernel strictly enforces that
> indirect function calls use a function pointer type that matches the
> target function. I ran into the following type mismatch when running
> BPF self-tests:
>
>    CFI failure at bpf_obj_free_fields+0x190/0x238 (target:
>      bpf_crypto_ctx_release+0x0/0x94; expected type: 0xa488ebfc)
>    Internal error: Oops - CFI: 00000000f2008228 [#1]  SMP
>    ...
>
> As bpf_crypto_ctx_release() is also used in BPF programs and using
> a void pointer as the argument would make the verifier unhappy, add
> a simple stub function with the correct type and register it as the
> destructor kfunc instead.
>
> Signed-off-by: Sami Tolvanen <samitolvanen@...gle.com>

Acked-by: Yonghong Song <yonghong.song@...ux.dev>